vga optimization (Glauber Costa)

Hypervisors like KVM perform badly while doing mmio on
a loop, because it'll generate an exit on each access.
This is the case with VGA, which results in very bad
performance.

In this patch, we map the linear frame buffer as RAM,
make sure it has dirty region tracking enabled, and then
just let the region to be written.

Cleanups suggestions by:
  Stefano Stabellini <stefano.stabellini@eu.citrix.com>

Signed-off-by: Glauber Costa <glommer@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>



git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@5793 c046a42c-6fe2-441c-8c8c-71466251a162

1 files changed, 6 insertions, 0 deletions

diff --git a/exec.c b/exec.c
index 4d39eaaf20..43a1b78f46 100644
--- a/exec.c
+++ b/exec.c
@@ -1887,6 +1887,12 @@ int cpu_physical_memory_get_dirty_tracking(void)
     return in_migration;
 }
 
+void cpu_physical_sync_dirty_bitmap(target_phys_addr_t start_addr, target_phys_addr_t end_addr)
+{
+    if (kvm_enabled())
+        kvm_physical_sync_dirty_bitmap(start_addr, end_addr);
+}
+
 static inline void tlb_update_dirty(CPUTLBEntry *tlb_entry)
 {
     ram_addr_t ram_addr;